Thermostatic radiation indicator



April 1s, 1933.

l P.` GARMS ET AL THERMOSTATIC RADIATION INDICATOR Filed Jan. 2, 1932 .2 lSheets-Sheet 1 T H EIR ATTORNEYS.

April 1s, 1933.'

P. GARMS ET Al.' 1,904,129 I THERMOSTATIG RADIATION INDICATOR Filed Jan.. 2,'1932 2 Sheets-Sheet -2 Y sectional view taken on Patented pr. I8, 1933 rnTmcAm, or maw Yonx, .aim axiomas Your, AssIGNoas To ELECTRICAL TESTING vA OOBPOBATIQN OF NEW YORK mwrs moeLm or rLusHnw, maw LanonAToaIEs, or Naw roux, N. Y.,

THEBMOSTATIC RADIATION INDICATOR Application mea :sanary 2, issn. .serial 1ro. 534,498.

The present invention has for its object to rovide an apparatus for use in testing the fe of laments in incandescent electric lamps and accurately recording the length of time such filaments will burn under a given current rating.

In'r the commercial manufacture. of electric lamps, it is desirable to determine from time to time their normal life expectancy. This is ordinarily accomplished by performing life tests against current on samples of the lamps manufactured, and these tests require careful observations as to the periods of time over-which the filaments extend un-v til they are disrupted.- v c The -present invention has f or an obyect to provide a device for the testing of erectric lamp iilaments, which will require minimum attention onA the part of the operator 1n performing the tests and will provide an automatic registration of the elapsed time.

To these and other ends our invention comprises further improvements all as will be more fully described in the followin specification, the novel features thereof being particularlypointed out in the appended claims.

In the drawings: y Fig. 1 is a sc ematic illustration of one embodiment of the invention; Fig.'2 is a lan view of the temperature-controlled switc of Fig. 1,V located within a housing, a portion of the cover plate being broken away; Fig. 3 is a cross-sectional view taken on the line 3-3 of Fig. 2, includin additional parts not shown in Figs. 1 an 2; Fig. 4 is a fragmentary plan view of the housing cover plate Fig. 5 is an enlarged fragmentary crossthe line 5 5 of Fig. 2; Fig. 6 is a schematic illustration of another embodiment of thel invention; and Fig. 7 isv a view in elevation showing a mechanical assembly of the thermostat in relation to an electric lamp to be tested.

In Fig. l we have shown incandescent electric lamp 1 which is preferablydisposed in a vertical position and a temperature-controlled switch 2 comprisingan arcuate thermal' expansion-strip 3 surrounding a portion of the lamp and osed in a horizontal' position'. 'IKhe radius o curpre erably of the bimetallic typ`e com through the schematically an vature of the expansionstri 3 .-is such as to accommodate lamps of di erent size and type. In the embodiment of the invention shown,

neck-portion of the lamp, although it is understood that it may surround the body' pro er. The thermal expansion-strip 3 is rising an outer element 4 made of a metal 'c material having a relatively low coeiiicient of expansion, such as the allo known in the trade as,Invar, and an inner `element 5 made of a different metal having 'a relatively high coeiiicient of expansion, such as brass. A conducting supporting strip or bar 6 may be secured by rivets 7 to one end of the strip' and serve as a support, and at its other extremity or free end another strip 10 may be attached by lrivets 9 and serve as a circuit contact Amember arranged in one side of the circuit of an automatic timing device or time register, such as an electric clock 14. One terminal of the latter is connected by a conductor 12 to the bar 6 b the binding screw 11. The other termina -of the register is Aconnected through a conductor 15 to one side the expansion-strip 3 surrounds the in establishing a -circuit connection to per-fl mit current to flow from the source 16 switch 2 and the time register 14 when the strip 3 is expanded, and in interrupting such connection to check the flow of such current when the expansion-strip contracts. The arm 19 is carried by a block 23 of insulating. material and is formed at one vside with an extension 24 carrying another set screw 25 which forms a hack-stop also cooperating with the arm 10 in a manner to be presently understood. The block 23 is formed with an aperture 26 through which extends a journal pin 27 whereby the bearing against. the contact 21, when actuating arm 10.

range of'lamps of varying wattage', because This construction of the switch 2 with particular reference to the oscillating character of the spaced elements 21 and 25 is an important feature of the invention in that it permits the thermal-strip 3 to expand freely to its fullest extent asdetermined by the heat radiated by the lamp filament 13 when current is passed therethrough. The amount of expansion of the strip 3 depends on the size or wattage of a particular lamp undergoing test, or the amount of heat radiated, and the switch 2 therefore permits life tests to be performed with accuracy over a wide a comparatively quick return or contraction of the thermal member strip 3 from its expanded position is assured in each case @and very little time elapses before the breakingv of the circuit occurs by, the separation of contacts 10 and 21, when the heat radiated from the lamp bulb is interrupted. by the breakdown or burning out of its filament.

The adjacent ends of the 'set screws 21 and 25 are so adjusted in the first instance that -a quick closing of the cooperating contacts 10-and 21 occurs when current is supplied to the lamp filament.

To shorten the timerequired in performing life tests on electric lamp filaments, the latter are tested against Aan adverse current or over-voltage condition, which may be 150% of the normal current or. voltage to which such filaments are subjected in servi ice, the normal life of a given filament being computed by an empirical formula ap- 4the required value.

plicable to the particular type of lamp undergoing study, using the. data obtained in the over-voltage test. In order that the current to be. passed through the filament may be derived from the usual house lighting circuit, -we provide the apparatus with means for increasing the normal live voltage from such source and our testing apparatus in- -cludes means for varying or adjusting the over-voltage applied to a lamp filament to As. shown in Fig. 1, our apparatus comprises a step-up transformer 28 the primary or low-tension winding 29 of which is connected by conductors 30 and 31 tothe output terminals' of a double pole switch 32, which when closed is connected by conductors 34 and 35 to the terl minals of the current source 16. The secsated f or in ondary or high-tension winding 36 of the nected to the taps 37. The switch 45 permits the desired tap to be connected in circuit with the lamp filament and the proper voltage to be applied to said filament.

From the above description, it' becomes apparent that upon the closing of the switch 32, the heat generated by the lighted lament 13 and radiating from the lamp bulb will cause the thermal-strip 3 to expand, by reason of its bimetallic construction, to quickly close the pair of contacts 10 and 21. The lighting of the filament 13', therefore, causes an almost immediate passage of current through the time register or clock 14, causing it to start. In the embodiment of the invention shown in the drawings, the clock 14 is provided with a dial having its larger divisions calibrated in'steps of sixty minutes and its smaller divisions in steps of one minuteduration, whereby the elapsed time may conveniently be read from the dial l At the beginning of a -test the two clock hands are preferably adjusted (prior to the closing of the switch 32) to point to the zero position on the dial, so that thereafter the clock 'reading is an indication of the actual length or duration of the test. Y.

The iow of excess current through the filament 13 will in time cause it to burn out, and almost in immediate response to the interruption of current through the filament there occurs a corresponding ment or contraction of the thermal-strip. 3, which opens the contacts 10 and 21 to disconnect the clock circuit an'd interrupt its movement. The hour and minute hands, in their position of arrest, then indicate lthe actual period of time the lamp filament 13 was in full service. It wil-l be noted that any sluggishness in the expanding and contracting of the thermal member 1s compenthe record made, because whatever time is lost in the closing of the switch contacts10 and 21,- at the start of the test, is offset by the time required to open said contacts when the test isterminated.

. As shown in Figs. 2 and 3, the temperature-controlled switch 2 and parts associated therewith are preferably mounted'within a housing 47 comprising a recessed bottom member 49 and a cover plate 50 secured thereto by screws 51. These parts 49 and 50 are made of suitable insulating material,

such as bakelite,`and the bottom member 49 inward move- .desired shape. The supporting bar 6 is secured, as by the screws 11 and 52, to a side wall of the recess 54, and one of the screws is vutilized asa binding post for the conductor 12. The members 49 and 50 are formed with corresponding o enings 55 and 56 to permit insertion o' the stem or body of a lamp through the interior of the temperature-controlled member 3, and a suitable number of ventilation apertures 57 are circularly disposed in both members 49 and 50 to facilitate the circulation of air into c011- tact With the thermal member 3.

The insulating block 23 carrying. the pair of stops 2l and 25 is supported freely in the recess 54, as more clearl shown in Fig. 5, on its journal pin 27. T e latter is rigidly v secured to the bottom member 49 by a screw portion 58 and a nut 59 and above said nut a bearing washer 60 provides a seating surface for theblock- 23. As loosely fitting cap 61 surrounds theupper end portion ofthe pin 27 and hasta lower flanged end 62 bearing. against the block 23. This cap 61 extends through an opening 63 in the cover plate 50, in which opening it is free to move when the block 23 is actuated by the thermal 64 mounted on the member 3. A dat spring d th e upper en o e cover 50 bears against t `cap 61 to provide sufhcient friction to prevent displacement of the block ..3 other than that caused by the expansion or contraction of the member 3. T desired the bearing pressure of the spring may be regulated by a screw 65 which engages athreaded stud 66 carried by the cover plate 50; v

An opening 69 formed through `the side wall of the bottom member 49 accommodates the conductors 12 and 17 leading to the switch 2, the former leading directly to the conductingbar 6, and the uatter being connected through a binding post 76 to one end of a pigtail or coil wire 17a, the other extremity of which is connected by the binding screw 20 to the bar 19. This coil 17 ais made of line Wire to avoid any offsetting torque from being applied to the block 23.

As it may be desirable on occasion to either make or break the clock circuit manually, we provide the switch block 23 with a pin 72 which extends exteriorly of the casing and preferably projects through an arcuate slot 71 in the cover 50.

Fig. 6 shows a modification of our invention in which the temperature-controlled switch 2', instead of causing an interruption 'of current flow through the timing device closed. In this modification the register isl located in the output circuit of the transformer and its movement is arrested by opening the input circuit of the transformer.

The parts of the switch mechanism here villustrated are identical with those heretofore described and for the purpose of brevity, corresponding numerals, primed, are employed to indicate the corresponding parts. It will be noted in F ig. 6 that the block 23' is in an inverted position from that shown in Figs. 2 and 3. Thus, the thermalV member 3 operates to open the cooperating contacts 10 and 21 when it starts to expand, and vice versa to close said contacts when it starts to contract.

VA conductor 75 connects the conducting bar 19 to one output terminal.` of a doublepole switch 76 and a conductor 77 connects the supporting bar 6 to one end of the winding 78 of a relay 79, the other end of said 80 to the other output terminal of the switch '76. The input terminals of the switch 76 are connected to the A. C. lighting source 83. The relay 79 has a movable armature 84 which normally engages a back Contact 86 under the influence of spring 90. This pair of normally closed contacts 84 and 86 is connected in the circuit of the primary or low tension input Winding 88 of the step-up transformer 89, the conductors 81, 87, 85 and 82 connecting said winding and pair of contacts in series and across said output terminals of the switch 76, so that, when the latter is closed, current normally fiows through'said Winding 88. Upon energize.- tion of the relay winding 78 by aclosure of the contacts 10 and 21', the relay armature 84 is attracted and the transformer input cir-v cuit interrupted. Provision is made for short circuiting the contacts 84 and 86 when desired, by the closing of a switch 92 the terminals of which 'are connected by conductors 93 and 94, respectively, to the conductors 85 and 87 leadin to said contacts 84 and 86.

The secondary or high-tension output winding 95 of the transformer 89 is provided at one side portion with several taps `96 having terminals 97 which may-take the form of suitable sockets into which terminal contacts 98, in the form'of suitable plugs, may be inserted. The ends of the lamp filament, indicated by 101` terminate in the usual shell and center contacts and these are connected through the usual lamp socket (not shown) in circuit with the output of the transformer by conductors 99 and 100, the plug 98 to which one of said conductors is connected being inserted into the kjack 97 providing the required voltage to be applied for testing purposes across the lamp 7 4. The

.clock 102 is connected through one of its terminals by a conductor 103 to the winding 95 and through its other terminal by a conquired voltage for proper operation of saidl clock. s

In preparation for a test with the circuit arrangement of Fig. 6, the switch- 76 is -closed and the switch `92 is also closed to permit current to flow from the source 83 through the low-tension winding of the transformer 89 and consequently fiow of current in the secondary circuits of said transformer to cause the filament of lamp 74 to become lighted and to start the register 102.

Closing of the switch 92 is only necessary momentarily to short circuit the relay contacts 84 and 86 to permit said lighting of the lamp filament and operation of the register, which would not take place, should the con.- tacts 10 and 21 touch and the relay vwinding 78 be correspondingly energized upon closingrthe switch 76. Instead of closing the switch 92, the block 23` may be operated manually, if desired, to break the contact at the switch 2, this preventing the relay winding 78 from being energized at the start of the test.

The heat created when current flows through the lamp filament 101, causes the thermal strip 3 to press on the stop-25 and tilt the boek 23, which causes contact 21 to follow the movement of its cooperating contact 10. The switch 92 remains open during the test. Upon the breaking down of the lamp filament 101, the expansion-strip 3 contracts, thereby almost immediately thereafter closing the contacts 10 and 21 and establishing a circuit through the relay 78. This opens the contacts 84 and 86 and interrupts the flow of current through the main supply, whereupon the mechanism of the clock 102 is arrested, the position of its hands indicating the life-periodof the filament 101.

The embodiment of the invention shown in Fig. 6 possesses the advantage that a number of lamps may be tested with the use of a singe clock.- A number of lamps may be connected in parallel with the lamp 74 or several lamps or groups of lamps may each be connected by ak suitable tap 96 of the transformer 89, each lamp being provided with a separate temperature-controlled switch 2f and separate relay 78, each of such relays controlling the flow of current from ,the source 83 to the transformer 89. When a iiament of any of the several lamps burns out, the register 102 is caused to stop and the current is interrupted through all of the filaments. A reading of the register then gives the period of time over which the single disrupted filament extended. If desired this lamp may be replaced by a new one, Grits thermal switch vmay be disconnected by merely moving the switch block to open its pair of contacts 10 and 21. and the tests continued on the remaining filaments. A reading is taken from the register 102 each time a filament burns out, and by averaging the successive readings after breakdown of a plurality of filaments, the life-period of a particular filament in normal service can be determined with considerable accuracy.

Fig. 7 shows'a practical operative assembly of the parts. Here a lamp 105 is shown supported from a conventional socket 106 carried by the upper bracket portion 107 of a supporting frame 109. The housing 47 containing the temperature-controlled switch is properly positioned, relatively to the lamp, by securing said housing to another bracket 110 forming part of said frame. While this form of apparatus may be used for supporting a single lamp to be testedand heat-controlled switch therefor, it is understood that in practice life tests may be performed simultaneously on a large number of lamps.

lIn such cases the lamps with their respective temperature-controlled switches may be mounted in successive rows on appropriate racks or like framework.

It is understood that the invention is not limited to the particular embodiments shown and described herein, and that other arrangements are possible without departing from its principle.

While we have described the invention in connection with incandescent lamps having filaments, it will be understood that specific reference to such lamps is for illustrative purposes only as indicative of a heat radiating body which in practice might be any article which when in use is subject to variants of temperature andthe duration of which it may be desirable to measure. As a further exampe mention is made of the gaseous type of lamp in which a luminous glow is obtained" by the passage of current between electrodes within the bulb.

Vhat we claim is:

- 1. In an apparatus for testing electric lamps, the combination with a lamp, and means for supplying current to said lamp; of a temperature-controlled switch comprising an arcuate thermal expansion member disposed adjacent to said lamp, andcircuit contacts operated by said member to close under the effect of heat radiated from said lamp upon illumination and to open upon the termination of said illumination; a timing device, and electrical means controlled by said contacts for controlling the operation of the timing device.

2. In an apparatusv for testing electric lamps, the combination with a lamp, and means for supplying current therethrough; of a temperature-controlled switch comprising an arcuate expansion member surrounding said lamp so as to be expanded by the heat radiated by the lamp when lighted and to contract when current through the lamp isinterrupted, and contact means operated Y said contact means being movable as a whole to permit its operation substantially at the start of the expansion and the contraction of said member; a timing device, and electric means controlled by said switch for controlling the operation of said timing device.

3. The combina-tion with an electric lamp and means` for supplying current thereto; of

' a temperature-controlled switch comprising radiated heat when current is caused to low an arcuate expansion-strip surrounding said lamp and having a free end, a, pivotal mounting, two spaced elements on said mounting adapted to be relatively fixed at opposite sides of said free end, said mounting being caused to pivot in either direction under the iniiuence of said expansion-strip, one of said elements cooperating as a contact with said strip and a housing for said parts; a timing device, and electrical means controlled by said cooperating contacts for controlling the operation of said timing device.

4. The combination with an electric lamp and means for supplying current thereto; of a temperature-controlled switch comprising an expansion-strip surrounding said lamp .and expansible under the iniiuence of through said lamp and contractible when such current is interrupted, a contact carried by said strip, a pivoted member carrying two spaced stop elements located at opposite sides of said contact, one of said i stops operating as a circuit contact in cooperation with said expansion-strip contact, a ventilated housing for said parts, and means for manually operating said pivoted member exteriorly of said housing; a timing device, and electrical means controlled by said cooperating contacts for controlling the operation of said timing device.

5. In an apparatus for testing electric lamps, the combination with an electric lamp, and means for supplying current therethrough; of a temperature-controlled switch comprising an arcuate thermal-strip disposed around said lamp to permit it to expand under the iniuence of radiated heat when current is caused to flow through said lamp and to contract when such current is interrupted, and a pair'of cooperating contacts adapted toalternately open and close upon expansion and contraction of said thermal-strip; a time indicating device, and means for supplying current to said device through said switch.

6. In an apparatus for testing electric lamps, the combination with a lamp, and means for supplying current therethrough; of a temperature-controlled switch comprising a thermal expansion member disposed adjacent Asaid lamp, and circuit contacts o erated by said member to close under the-e ect of heat radiated from said lamp upon illumination andto open upon the termination of said illumination; a relay in circuit with said switch, and' a timing device controlled by said relay. i 7 In an apparatus for testing electric lamps, the combination with an electric lamp, and means for supplying current therethrough; of a temperature-controlled switch compirsing an arcuate thermal-strip disposed around said lamp to permit it to contract from an expanded position when current through said lamp and heat "radiated therefrom are interrupted, and contact means operated under the iniiuence of said expansion-strip when contracting; and a timlng device controlled by said contact means.

8. In an apparatus for testing electric lamps, the combination with a lamp and electrical means for supplying current I through said lamp; of a temperature-controlledswitch comprising an expansion-.strip surrounding said lamp and adapted to ,cointract from an expanded position when current through said lamp and heat Iradiated therefrom are interrupted, and contact means .operated under the influence of said strip upon contracting, a timing device also operated by said electrical means, and a relay controlled by said switch and controlling said electrical means.

9. In a vtesting device for electric lamps,

the combination with a lamp, a step-up transformer, an' input circuit supplying current to p said transformer, and an output circuit supnlying current from said transformer to said lamp` of a timing device operated from one of said circuits., a thermostat actuated by heat from the lamp upon illumination and by interruption of said heat when the lamp filament burns out, and electrical means controlled by said thermostat for controlling the operation of said timing` device.

10. In an apparatus for testing electric lamps, thecombination with a lamp, of a 'timing device, means for supplying current to said lampV and to said timing deviceVa thermostat actuated by interruption of the heat radiated from said lamp upon cessa- Y tion of current-therethrough, and electrical means controlled b v said thermostat for controlling said supply means. 11|. In an apparatus for testing electric lamps, the combination Vwit-h a lamp, and means for supplying current to said lamp, of a thermostat actuated by interruption of the heat radiated romsaid lamp upon cessation of current therethrough, a timing device, means for supplying current, to said device, and means controlled by said thermo- A stat for controlling said second supply means. 1. l

and means for supplying current thereto; of.

a temperature-controlled switch comprising an arcuate expansion-strip surrounding said lamp and expansible under the iniuence of radiated heat when current is caused to How through said lamp and contractible when such current is interrupted, a. contact carried by said strip, a pivotal member carrying two spaced stop elements located at opposite sides of said contact, one-of said stops op' erating as a circuit contact in cooperation with said expansion-strip contact, a housing for said parts, adjustable braking means cooperating with said member and mounted on said housing, and means for manually operating said member exteriorly of said housing; a timing device, and electrical means controlled by said cooperating cont-acts for controlling the operation of said timing device.

14. In an apparatus for testing electric lamps, the combination with a lamp, and

' means for supplying current to said lamp;

of a temperature-controlled switch comprlsin a thermal expansion member disposed adJacent to said lamp sofas to be expanded by the heat radiated bythe lamp when lighted and to contractwhen current through means cont-rolled by said switch for controlling the operation of said timing device.

In testimony whereof, we have signed this specification.

PETER GARMS.` GEORGE lLEWIS DIGGLES.

the lamp `is interrupted, and contact means operated by said member to close upon the movement of the latter in one direction and to'open upon its movement in the other direction; a timing device, and electrical means controlled by said switch for controlling the operation of said timing device.

15. In an apparatus for testing electric lamps, the combination with a lamp, and means for supplying current-to' said lamp; of a temperature-controlled switch comprlsing athermal expansion member disposed adJacent to said lamp so as to be expanded by the heat radiated by the lamp when lighted and to contract when current through the lamp is interrupted, and contact means operated by said member to close upon the movement of the latter in onedirection and to open upon its movement in the other direction, said contact means being movable as a whole under the influence of said memberv to permit its operation substantially at the start. of the expansion and the contraction of said member; -a timing device, and electric 

